1. Field of the Invention
This invention relates to flow control valves and more particularly to a valve used in the inlet or suction line of a compressor between the evaporator and the compressor of a refrigeration system.
2. Description of the Prior Art
Flow control valves, including check valves, are commonly used in refrigerant lines where pressure reversals can cause undesirable reverse flow. A check valve may be opened by a portion of the pressure drop which causes flow in the line. Various types of check valves are known, such as those which close only when flow exceeds a maximum desired rate, electrically operated, which require no pressure drop to remain open, and remote pressure operated which are subject to a higher pressure source of refrigerant.
The Andersson U.S. Pat. No. 2,069,808 discloses a downstream controlled pressure regulator in which the valve stem is centered by a diaphram and having a filter in the inlet portion of the valve.
The Birch U.S. Pat. No. 2,105,876 discloses a downstream water pressure regulator having a cylindrical screen mounted between an interior wall and the removable cap in the inlet side of the regulator.
The Le Valley U.S. Pat. No. 2,661,893 discloses a control valve operated by external pressure in response to variations in discharge pressure.
The Robinson U.S. Pat. No. 3,744,751 discloses a check valve whose length of travel is controlled by a manual valve.
The Post et al. U.S. Pat. No. 3,788,776 discloses in FIG. 2 an inlet throttling valve which is closed in response to pressure in line 68 and in which the spring 56 assists in opening the valve.
The Hoffman U.S. Pat. No. 4,406,588 discloses a suction regulator for a compressor in which full opening of the valve is dependent on discharge pressure from the compressor.
The Laucks et al. U.S. Pat. No. 4,227,380 discloses a combination valve for the inlet of a compressor including a manually operable valve, an automatically controlled stop valve, an automatically controlled check valve, and a strainer on the inlet side of the valve.
The Hart U.S. Pat. No. 4,473,093 discloses a fluid control valve which is operated in response to an external "control" gas pressure.